What is the main cause of seismic waves?
What is the main cause of seismic waves?
Seismic waves are usually generated by movements of the Earth’s tectonic plates but may also be caused by explosions, volcanoes and landslides. When an earthquake occurs shockwaves of energy, called seismic waves, are released from the earthquake focus.
What causes wave erosion?
As waves reach shallow water near the ocean shore, they begin to break. As the breaking waves hit the shoreline, their force knocks fragments off existing rock formations. Another way waves causes erosion is by forcing water into cracks in the rocks at the shoreline.
Where does wave erosion occur?
Waves erode sediments from cliffs and shorelines. The sediment in ocean water acts like sandpaper. Over time, they erode the shore.
How do Seawalls destroy beaches?
First, they choke the sediment eroding down the bluffs that would otherwise replenish beaches. The seawalls reflect the power of retreating waves which rip away the body of the beach and drown it by carrying the valuable beach sand out to sea.
How do you reinforce a cliff?
Some techniques also protect the foot of the cliff against marine erosion, a key factor in strengthening cliffs….Techniques include:
- Cliff reshaping / profiling: changing the slope angle, and/or reducing cliff heights by removing unstable blocks.
- Cliff drainage: eliminating surface runoff and infiltration on the slope.
How does Cliff regrading work?
Cliff regrading is where the gradient of the cliff is reduced so that damage of costal erosion is reduced as the destructive waves with just go up the cliff and just back again.
How does Cliff drainage protect the coastline?
Cliff drainage: eliminating surface runoff and infiltration on the slope. Concrete buttress and riprap strips: reinforced concrete support on undercut rocky zone on the cliff or the foot; ripraps (strip of stones and concrete) are placed at the foot of the cliff to prevent marine erosion.
Is Cliff drainage a soft engineer?
Draw a labelled diagram to show how cliff regrading works. This is a method of soft engineering because it involves working with the natural environment, is low cost and is sustainable. Work is also carried out to drain the cliff because by taking the water out it reduces the risk of landslides and mass movement.
What are the advantages and disadvantages of Cliff regrading?
Soft Engineering – Cliff Regrading
| Soft Engineering – Cliff Regrading | |
| Advantages Cliff becomes more stable Less prone to unexpected movement | Disadvantages May be impractical if valuable land use exists on cliff top Ongoing maintenance costs |
What are the disadvantages of rock Armour?
Hard engineering options
| Type of defence | Advantages | Disadvantages |
|---|---|---|
| Rock armour or boulder barriers – large boulders are piled up on the beach. | Absorb the energy of waves. Allows the build up of a beach. | Can be expensive to obtain and transport the boulders. |
Does rock Armour look natural?
The natural looking solution provides protection to residential properties, holiday homes and businesses protected from flooding, as well as increased safety for employees, residents and tourists during storm periods.
Is rock armor soft or hard engineering?
Hard engineering – sea walls, groynes, rock armour Hard engineering involves the building of entirely ARTIFICIAL structures using various materials such as rock, concrete and steel to reduce or stop the impact of coastal processes.
Is Rock Armour hard engineering?
Most seawalls are made out of concrete or stone and are built parallel to the coast. They have been constructed in thousands of locations throughout the world. Rip-rap/rock armour – Boulders piled up against the coast that absorb the energy of the waves. Gabions – wire cages filled with rocks to absorb wave energy.
What are examples of soft engineering?
Soft engineering coastal protection (erosion)
- Beach nourishment. Replacing lost beach material from a natural store either offshore (beach rebuilding) or from downshore along a stretch of longshore drift (beach recycling)
- Beach reprofiling.
- Living shoreline barrier.
What type of engineering is rock Armour?
Rock armour or rip-rap involves placing large boulders in front of a cliff or sea wall to absorb the energy of waves. Rock armour is a cheaper solution than seawalls to deflect the wave energy.